473 lines
14 KiB
Python
473 lines
14 KiB
Python
from __future__ import annotations
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from typing import Dict, Mapping, List, Set
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from enum import Enum
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class UnificationError(Exception):
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def __init__(self, msg):
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super().__init__(msg)
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class Type:
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def find(self):
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return self
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def unify(self, _):
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raise NotImplementedError()
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def subst(self, _):
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raise NotImplementedError()
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def check(self):
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pass
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class TVarType(Enum):
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UNDETERMINED = 1
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SEQUENCE = 2
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RECORD = 5
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TUPLE = 6
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LIST = 8
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def __le__(self, other):
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if self.__class__ is other.__class__:
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return (other.value % self.value) == 0
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return NotImplemented
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def unifier(self, other):
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if self.__class__ is not other.__class__:
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raise NotImplementedError()
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if self <= other:
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return other
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elif other <= self:
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return self
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else:
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raise UnificationError(f'cannot unify {self} and {other}')
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class TVar(Type):
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next_id = 0
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def __init__(self, vrange=None):
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self.type = TVarType.UNDETERMINED
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self.rank = 0
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self.parent = self
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self.checked = False
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self.fields = {}
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self.range = vrange
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self.id = TVar.next_id
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TVar.next_id += 1
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def check(self):
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if self.checked:
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return
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self.checked = True
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if self.range is not None:
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ty = self.find()
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# maybe we should replace this with explicit eq
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if ty is not self and ty not in self.range:
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raise UnificationError(
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f'{self.id} cannot be substituted by {ty}')
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def subst(self, mapping: Mapping[int, Type]):
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# user cannot specify fields...
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# so this is safe
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if self.id in mapping:
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return mapping[self.id]
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return self
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def __str__(self):
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s = self.find()
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if isinstance(s, TVar):
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if len(s.fields) > 0:
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fields = '{' + ', '.join([f'{k}: {v}' for k,
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v in s.fields.items()]) + '}'
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else:
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fields = ''
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return str(s.id) + fields
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else:
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return str(s)
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def find(self):
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root = self
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parent = self.parent
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while root is not parent and isinstance(parent, TVar):
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_, parent = root, root.parent = parent, parent.parent
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if isinstance(parent, TCall):
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parent = parent.find()
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return parent
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def unify(self, other):
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x = other.find()
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y = self.find()
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if x is y:
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return
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if isinstance(y, TVar) and isinstance(x, TVar):
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# unify field type
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x.type = x.type.unifier(y.type)
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# unify fields
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for k, v in y.fields.items():
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if k in x.fields:
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x.fields[k].unify(v)
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else:
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x.fields[k] = v
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# standard union find
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if x.rank < y.rank:
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x, y = y, x
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y.parent = x
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if x.rank == y.rank:
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x.rank += 1
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elif isinstance(y, TVar):
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# check fields
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if isinstance(x, TVirtual):
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obj = x.obj.find()
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self.unify(obj)
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elif isinstance(x, TObj):
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if y.type not in [TVarType.UNDETERMINED, TVarType.RECORD]:
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raise UnificationError(f'Cannot unify {y} with {x}')
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for k, v in y.fields.items():
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if k not in x.fields:
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raise UnificationError(
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f'Cannot unify {y} with {x}')
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u = x.fields[k]
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v.unify(u)
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elif isinstance(x, TList):
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if y.type not in [TVarType.UNDETERMINED, TVarType.SEQUENCE, TVarType.LIST]:
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raise UnificationError(f'Cannot unify {y} with {x}')
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for k, v in y.fields.items():
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assert isinstance(k, int)
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v.unify(x.param)
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elif isinstance(x, TTuple):
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if y.type not in [TVarType.UNDETERMINED, TVarType.SEQUENCE, TVarType.TUPLE]:
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raise UnificationError(f'Cannot unify {y} with {x}')
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for k, v in y.fields.items():
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assert isinstance(k, int)
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if k >= len(x.params):
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raise UnificationError(f'Cannot unify {y} with {x}')
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v.unify(x.params[k])
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y.parent = x
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else:
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y.unify(x)
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def __eq__(self, other):
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s = self.find()
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o = other.find()
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if not isinstance(s, TVar):
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return s == o
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if isinstance(o, TVar):
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return s.id == o.id
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return False
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class FuncArg:
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def __init__(self, name, typ, is_optional):
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self.name = name
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self.typ = typ
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self.is_optional = is_optional
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def __str__(self):
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return f'{self.name}: {self.typ}' + ('?' if self.is_optional else '')
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class TCall(Type):
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def __init__(self, posargs: List[Type], kwargs: Dict[str, Type], ret: Type):
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self.calls = [[posargs, kwargs, ret, None]]
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self.parent = self
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self.rank = 0
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self.checked = False
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def check(self):
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if self.checked:
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return
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self.checked = True
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self.calls[0][3].check()
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def find(self):
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root = self
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parent = self.parent
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while root is not parent and isinstance(parent, TCall):
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_, parent = root, root.parent = parent, parent.parent
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if parent.calls[0][3] is None:
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return parent
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return parent.calls[0][3]
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def unify(self, other):
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y = self.find()
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if y is not self:
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y.unify(other)
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return
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x = other.find()
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if x is y:
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return
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if isinstance(x, TCall):
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# standard union find
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if x.rank < y.rank:
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x, y = y, x
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y.parent = x
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if x.rank == y.rank:
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x.rank += 1
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x.calls += y.calls
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elif isinstance(x, TFunc):
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fn = x
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for i in range(len(y.calls)):
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if not x.instantiated:
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fn = x.instantiate()
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posargs, kwargs, ret, _ = y.calls[i]
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c = y.calls[i]
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c[3] = fn
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all_args = set(arg.name for arg in fn.args)
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required = set(arg.name for arg in fn.args if not
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arg.is_optional)
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fn.ret.unify(ret)
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for i, v in enumerate(posargs):
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arg = fn.args[i]
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arg.typ.unify(v)
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if arg.name in required:
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required.remove(arg.name)
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for k, v in kwargs.items():
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arg = next((arg for arg in fn.args if arg.name == k), None)
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if arg is None:
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raise UnificationError(f'Unknown kwarg {k}')
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if k not in all_args:
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raise UnificationError(f'Duplicated kwarg {k}')
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arg.typ.unify(v)
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if k in required:
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required.remove(k)
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all_args.remove(k)
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if len(required) > 0:
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raise UnificationError(f'Missing arguments')
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elif isinstance(other, TVar):
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other.unify(self)
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else:
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raise UnificationError(f'Cannot unify a call with {other}')
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class TFunc(Type):
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def __init__(self, args: List[FuncArg], ret: Type, vars: List[TVar]):
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self.args = args
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self.ret = ret
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self.vars = vars
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self.instantiated = False
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self.checked = False
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def check(self):
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if self.checked:
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return
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self.checked = True
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for arg in self.args:
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arg.typ.check()
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self.ret.check()
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def subst(self, mapping: Mapping[int, Type]):
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if len(mapping) == 0:
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return self
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return TFunc(
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[FuncArg(arg.name, arg.typ.subst(mapping), arg.is_optional)
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for arg in self.args],
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self.ret.subst(mapping),
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self.vars)
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def instantiate(self):
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mapping = {v.id: TVar(v.range) if isinstance(v, TVar)
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else TVar() for v in self.vars}
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result = self.subst(mapping)
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result.instantiated = True
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return result
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def __str__(self):
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return f'({", ".join(str(arg) for arg in self.args)}) -> {self.ret}'
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def unify(self, other):
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other = other.find()
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if other is self:
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return
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if isinstance(other, (TVar, TCall)):
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other.unify(self)
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elif isinstance(other, TFunc):
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if len(self.args) != len(other.args):
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raise UnificationError(
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f'cannot unify functions with different parameters')
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self.ret.unify(other.ret)
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for a, b in zip(self.args, other.args):
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if a.name != b.name or a.is_optional != b.is_optional:
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raise UnificationError(
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f'cannot unify functions with different parameters')
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a.typ.unify(b.typ)
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else:
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raise UnificationError(f'Cannot unify a function with {other}')
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class TObj(Type):
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def __init__(self, name: str, fields: Dict[str, Type], params: List[Type],
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parents=None):
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self.name = name
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self.fields = fields
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self.params = params
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self.checked = False
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if parents is None:
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self.parents = []
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else:
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self.parents = parents
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def check(self):
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if self.checked:
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return
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self.checked = True
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for arg in self.fields.values():
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arg.check()
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def subst(self, mapping: Mapping[int, Type]):
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if len(mapping) == 0:
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return self
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new_params = []
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changed = False
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for v in self.params:
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if isinstance(v, TVar) and v.id in mapping:
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new_params.append(mapping[v.id])
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changed = True
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else:
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new_params.append(v)
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if not changed:
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return self
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return TObj(self.name, {k: v.subst(mapping) for k, v in
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self.fields.items()}, new_params)
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def unify(self, other):
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other = other.find()
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if other is self:
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return
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if isinstance(other, TObj):
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if self.name != other.name:
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raise UnificationError(f'Cannot unify {self} with {other}')
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for k in self.fields:
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self.fields[k].unify(other.fields[k])
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elif isinstance(other, TVar):
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other.unify(self)
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else:
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raise UnificationError(f'Cannot unify an object with {other}')
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def __str__(self):
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if len(self.params) > 0:
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p = '[' + ', '.join(str(p) for p in self.params) + ']'
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else:
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p = ''
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return self.name + p
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def __eq__(self, other):
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o = other.find()
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if isinstance(o, TObj):
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if self.name != o.name:
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return False
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for a, b in zip(self.params, o.params):
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if a != b:
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return False
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return True
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return False
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class TVirtual(Type):
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def __init__(self, obj: Type):
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self.obj = obj
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self.checked = False
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def check(self):
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if self.checked:
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return
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self.checked = True
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self.obj.check()
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def __eq__(self, other):
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o = other.find()
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if isinstance(o, TVirtual):
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return self == o
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return False
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def unify(self, other):
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o = other.find()
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if isinstance(o, TVirtual):
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self.obj.unify(o.obj)
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elif isinstance(o, TVar):
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o.unify(self)
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else:
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raise UnificationError(f'Cannot unify {self} with {o}')
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def __str__(self):
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return f'virtual[{self.obj}]'
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class TList(Type):
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def __init__(self, param: Type):
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self.param = param
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self.checked = False
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def check(self):
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if self.checked:
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return
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self.checked = True
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self.param.check()
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def unify(self, other):
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other = other.find()
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if isinstance(other, TVar):
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other.unify(self)
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elif isinstance(other, TList):
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self.param.unify(other.param)
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else:
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raise UnificationError(f'Cannot unify list with {other}')
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def __str__(self):
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return f'List[{self.param}]'
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def __eq__(self, other):
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o = other.find()
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if isinstance(o, TList):
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return self.param == o.param
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return False
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class TTuple(Type):
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def __init__(self, params: List[Type]):
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self.params = params
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self.checked = False
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def check(self):
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if self.checked:
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return
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self.checked = True
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for p in self.params:
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p.check()
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def unify(self, other):
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other = other.find()
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if isinstance(other, TVar):
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other.unify(self)
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elif isinstance(other, TTuple):
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if len(self.params) != len(other.params):
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raise UnificationError(
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'cannot unify tuples with different length')
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for a, b in zip(self.params, other.params):
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a.unify(b)
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else:
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raise UnificationError(f'Cannot unify {self} with {other}')
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def __str__(self):
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return f'Tuple[{", ".join(str(p) for p in self.params)}]'
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def __eq__(self, other):
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o = other.find()
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if isinstance(o, TTuple):
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if len(self.params) != len(o.params):
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return False
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for a, b in zip(self.params, o.params):
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if a != b:
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return False
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return True
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return False
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